Multiple occupants in the vehicle fled from the scene and ran into the nearby brush. Agents arrested 11 of those who attempted to flee, including the driver, a juvenile and U.S. citizen.

"Additionally, agents encountered an individual in the cab of the truck who was unresponsive," law enforcement said. "Agents immediately attempted to resuscitate the individual and continued life-saving efforts until emergency medical services arrived.

"EMS transported the individual to a hospital nearby where he remained in critical condition."

At about 9:30 a.m. Saturday, the person died at the hospital.

Laredo Sector notified Homeland Security Investigations and CBP's Office of Professional Responsibility, and referred the incident to the State Attorney's Office. The driver is in the custody of the Webb County authorities.